PURPOSE: To form a broad scraping-off surface by arranging a number of scraper blades constituted of thin metal plates onto the periphery of a rotary disc and permitting said scraper blade to be bent freely from the intermediate part.

CONSTITUTION: A scraper blade 9A constituted of thin metal plates is installed, sepreading downward, onto the periphery of a rotary disc 8 driven by a motor 13. Said rotary disc 8 is equipped with vanes 11 to discharge the water in a space part 10, and a negative pressure is generated in the inside of the space part 10, and the scraper blade 9A constituted of thin metal plates is bent from the intermediate part and closely attached onto a cleaning surface 2. Therefore, a broad scraping-off surface can be formed, and the outer wall of a hull can be cleaned efficiently.